The present invention relates generally to communication networks, and, more particularly, to detecting leaky points within a network protocol domain.
In today""s information age, communication devices, such as computers and computer peripherals, are often internetworked over a data communication network. The data communication network typically includes a number of interconnected routers that route information from a source communication device to a destination communication device. The routers run various networking protocols in order to provide specialized communication services for the internetworked communication devices.
In order for the data communication network to provide a particular specialized communication service, such as multicasting or security, it is often necessary to set up a network protocol domain to specifically support that specialized communication service. The network protocol domain consists of a number of routers that run a common networking protocol and work together to provide the particular specialized communication service. For convenience, any router at the boundary of the network protocol domain that supports the networking protocol and is configured as a border router for that networking protocol is referred to as a border router. Any other router within the network protocol domain, including a router at the boundary of the network protocol domain that does not support the networking protocol or is not configured as a border router for that networking protocol, is referred to as an intermediate router. Because each network protocol domain is specific to a particular networking protocol, a particular router may be a border router for one networking protocol and an intermediate router for another networking protocol.
For some networking protocols, only the border routers in the network protocol domain are required to run the networking protocol. For other networking protocols, all routers in the network protocol domain are required to run the networking protocol. An intermediate router in the network protocol domain that is required to, but does not, run the networking protocol is considered to be a leaky point in the network protocol domain. Likewise, a border router that runs the same networking protocol in two or more overlapping network protocol domains is considered to be a leaky point in each of the overlapping network protocol domains. These leaky points may cause communication failures and other problems in the network protocol domain. For example, a leaky point in a network protocol domain set up for security may permit an outside communication device to access the network protocol domain without complying with security requirements. Also, a leaky point in a network protocol domain set up for multicasting may cause multicast routing problems within the network protocol domain.
Therefore, a technique for detecting leaky points within a network protocol domain would be useful.
In accordance with one aspect of the invention, a prober device transmits a probe message over a communication network. The probe message is propagated to a number of probed devices within the communication network. Each probed device that receives the probe message checks for leaky points within a network protocol domain of the communication network. Each probed device that detects a leaky point within the network protocol domain transmits a negative response message to the prober device to indicate that a leaky point was detected.
In accordance with another aspect of the invention, the prober device transmits the probe message to a number of neighboring devices in the communication network and monitors for a probe acknowledgment message from each of the neighboring devices. The prober device considers a neighboring device to be a leaky point within the network protocol domain if the prober device fails to receive a probe acknowledgment message from the neighboring device within a predetermined period of time. Furthermore, the prober device may receive one or more response messages from various probed devices within the communication network. A negative response message from a probed device indicates that the probed device detected a leaky point within the network protocol domain. In a preferred embodiment of the present invention, the negative response message includes a network address for each leaky point detected by the probed device. A positive response message from a probed devices indicates that the probed device is a border device within the network protocol domain. In a preferred embodiment of the present invention, the positive response message includes a network address for each exit interface supported by the border device.
In accordance with yet another aspect of the invention, a probed device receives the probe message from its neighboring device. Upon receiving the probed message, the probed device transmits a probe acknowledgment message to the neighboring device, and then proceeds to check for leaky points within the network protocol domain. The probed device transmits a negative response message to the prober device if the probed device detects a leaky point within the network protocol domain. In a preferred embodiment of the present invention, the negative response message includes a network address for each leaky point detected by the probed device. The probed device transmits a positive response message to the prober device if the probed device is a border device within the network protocol domain. In a preferred embodiment of the present invention, the positive response message includes a network address for each exit interface supported by the border device.